Polymers of an acrylate or methacrylate (hereinafter also referred to as “(meth)acrylate”) containing a polyfluoroalkyl group are useful for various surface treating agents since they have hydrophobic and lipophobic properties, and they have been used, for example, as a water repellent or oil repellent (see, for example, Patent Literature 1) and as an anti-resin adhesion agent for preventing adhesion of the epoxy resin used as an encapsulating agent of an electronic component to the lead or electrode (see, for example, Patent Literature 2). The fluoroalkyl group used in such surface treating agent has generally been a fluoroalkyl group containing 8 or more carbon atoms, and in particular, a perfluoroalkyl group.
However, biological and environmental accumulativity of perfluorooctanoic acid (PFOA) has recently attracted the attention, and in March 2003, U.S. Environmental Protection Agency (USEPA) published Preliminary Risk Assessment on the safety of the PFOA, and in January, 2006, USEPA advocated participation in the program for reducing environmental emission of PFOA and related chemicals as well as their precursors, and reducing their content in the products to the fluororesin producing companies, and the like. As a consequence, purchase and use of compounds having a perfluoroalkyl group with the chain length of 8 or more have become difficult.
A perfluoroalkyl group exhibits greatly reduced biological and environmental risk when the number of carbon atoms is up to 6. On the other hand, hydrophobic and lipophobic performance is markedly lost, and in particular dynamic hydrophobic and lipophobic performance is lost when the perfluoroalkyl group in the polymer contains up to 6 carbon atoms conceivably because the perfluoroalkyl group containing up to 6 carbon atoms does not form a crystalline structure as in the case of the perfluoroalkyl group containing 8 or more carbon atoms.